Intro: throughout the song I am pretty sure the same chords are played (E-A) although
the chorus may be different. The strumming pattern is similar in the verse, but switches
to all quavers/eighth notes before entering into the chorus.
E|-4-----4-----4-----4-----4---4\--0-----0-----0-----0-----0---0---|
B|-5-----5-----5-----5-----5---5\--2-----2-----2-----2-----2---2---|
G|-4-----4-----4-----4-----4---4\--2-----2-----2-----2-----2---2---|
D|-----------------------------------------------------------------|
A|-----------------------------------------------------------------|
E|-----------------------------------------------------------------|

Synth or guitar riff: this is played at the opening of the single version (or at least
the video version) which then suddenly cuts to the verse, which is a bit odd. Anyway, in
both the single and album versions it reappears at the end of the chorus and is 
introduced a bit more regularly. I think it is played as triplets, just give it a listen and you
will be fine!
  E                                   A
E|----0-----2--0-----4--0-----2--0--------0-----2--0--------0-----2--0-----|
B|-0-----0--------0--------0--------0--2-----2--------2--2-----2--------2--|
G|-------------------------------------------------------------------------|
D|-------------------------------------------------------------------------|
A|-------------------------------------------------------------------------|
E|-------------------------------------------------------------------------|

Guitar riff which is played to ease the change from A to E, and is also doubled in the
bass part (which otherwise just plays quavers/eighth notes which isn’t hugely exciting)
E|------------------------|
B|------------------------|
G|------------------------|
D|-----2------------------|
A|-2h4-----4--------------|
E|-------------0----------|